The project described here is a 3 channel capacitive touch sensor based on CAP1203 chip from Microchip which is a multiple-channel capacitive touch sensor controller. It has 3 x individual capacitive touch sensor inputs with programmable sensitivity for use in touch sensor applications. 3 x touchpads are provided on PCB to detect the touch. Each sensor input is calibrated to compensate for system parasitic capacitance and automatically recalibrated to compensate for gradual environmental changes. The CAP1203 includes Multiple Pattern Touch recognition that allows the user to select a specific set of buttons to be touched simultaneously. If this pattern is detected, a status bit is set and an interrupt is generated. The CAP1203 has Active and Standby states, each with its own sensor input configuration controls. Power consumption in the Standby state is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and cycle time. Deep Sleep is the lowest power state available, drawing 5µA (typical) of current. In this state, no sensor inputs are active, and communications will wake the device.

Connections Connector CN2

Pin1 VCC 3.3V or 5V DC
Pin2 SCL (Arduino UNO Analog Pin A5)
Pin 3 SDA (Arduino UNO Analog Pin A4)
Pin 4 Alert Interrupt Output for SMBus
Pin 5 GND

Note: Refer to datasheet of CAP1203 for the operation and configuration of the chip. Arduino example code and CAP1203 library from sparkfun.com are available as downloads to test the board.

Features

Power Supply 3.3V or 5V DC
Three (3) Capacitive Touch Sensor Inputs
Programmable Sensitivity
Automatic Recalibration
Calibrates For Parasitic Capacitance
Individual Thresholds for each Button
Multiple Button Pattern Detection
Power Button Support
Press and Hold Features for Volume-like Applications
Analog Filtering for System Noise Sources
RF Detection and Avoidance Filters
Digital EMI Blocker
Low Power Operations 5uA Quiescent Current in Deep Sleep. 50uA In Standby (Only Chip)
Samples One Or More Channels in Standby
I2C/SMBus Compliant Communication Interface
2 Easy to Mount Holes
Header Connector for Micro-Controller Interface
On-Board Power LED
PCB Dimensions 56.19MM X 33.90MM

Schematic

Parts List

NO	QNTY.	REF.	DESC.	MANUFACTURER	SUPPLIER	SUPPLIER PART NO
1	1	CN2	5 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5318-ND
2	1	C1	0.1uF/50V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
3	1	C2	10uF/6.3V SMD SIZE 1206	MURATA/YAGEO	DIGIKEY
4	1	D1	LED RED SMD SIZE 0805	LITE ON INC	DIGIKEY	160-1427-1-ND
5	1	R1	1K 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
6	3	R2,R3,R4	10K 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
7	1	U1	CAP1203 SOIC8	MICROCHIP	DIGIKEY	CAP1203-1-SN-ND